Comparison of heavy-ion transport simulations: Mean-field dynamics in a box
M. Colonna, Yingxun Zhang, Yongjia Wang, Dan Cozma, Paweł Danielewicz, Che Ming Ko, Akira Ono, M. B. Tsang, Rui Wang, H.H. Wolter, Jun Xu, Zhen Zhang, Lie-Wen Chen, Hui-Gan Cheng, Hannah Elfner, Zhao-Qing Feng, Myungkuk Kim, Youngman Kim, Sangyong Jeon, Chang‐Hwan Lee, Bao-An Li, Qingfeng Li, Zhu-Xia Li, S. Mallik, Dmytro Oliinychenko, Jun Su, Taesoo Song, Agnieszka Sorensen, Feng-Shou Zhang
Abstract
Within the transport model evaluation project (TMEP) of simulations for heavy-ion collisions, the mean-field response is examined here. Specifically, zero-sound propagation is considered for neutron-proton symmetric matter enclosed in a periodic box, at zero temperature and around normal density. The results of several transport codes belonging to two families (BUU-like and QMD-like) are compared among each other and to exact calculations. For BUU-like codes, employing the test particle method, the results depend on the combination of the number of test particles and the spread of the profile functions that weight integration over space. These parameters can be properly adapted to give a good reproduction of the analytical zero-sound features. QMD-like codes, using molecular dynamics methods, are characterized by large damping effects, attributable to the fluctuations inherent in their phase-space representation. Moreover, for a given nuclear effective interaction, they generally lead to slower density oscillations, as compared to BUU-like codes. The latter problem is mitigated in the more recent lattice formulation of some of the QMD codes. The significance of these results for the description of real heavy-ion collisions is discussed.